Georgetown University is conducting a natural history study of chronic non-A,non-B (NANB) hepatitis. The specific objectives of this proposal are: to develop a protocol and manual of operations for continuation of the current study on the long- term follow-up of transfusion-associated non-A,non-B (NANB) hepatitis; to conduct annual National Death Index (NDI) searches for all cohort members who were alive or not located at last follow-up; to obtain and code death certificates for all newly deceased; and to collect and abstract medical records for all hospitalizations that occurred since the last follow-up for newly deceased subjects. The searches will be conducted to determine whether a mortality difference between the infected cohort and the controls will develop with longer observation, as is suggested by the continued presence of chronic liver disease. Each surviving member will be contacted annually, and medical records for all hospitalizations that occurred since the last follow-up for those subjects who report liver disease will be collected and abstracted. The contacts will ensure that any liver disease that may have been missed through enzyme screening, or which may newly develop, will be identified.